Material for preparing metal surfaces for painting and the like



Patented Mars 6, 1934 MATERIAL FOR. PREPARING METAL moss FOR PAINTING AND THE James H. Gravel], American SUR- LIKE Elkins Park, Pa., assignor to Chemical Paint Company, Ambler,

Pin, a corporation of Delaware No Drawing. Application April 5,1932,

' Serial N0- 603,455 I 5 Claims. (01.148-8).

This invention relates to the art of preparing metallic surfaces for subsequent coating opera tionssuch, for example, as painting, and it has particular reference to the provision of an im-' proved material for the purpose specified.

As is well known in the art, it is customary to prepare metallic surfaces for a-painting operation by applying thereto various solutions which are adapted to dissolve and loosen extraneous matter such as rust or oiland then to remove the resultant residue by wiping or washing. So

lutions ofthe kind described are made up by the manufacturer in condition for immediate use. In other words, because of the character of the solutions heretofore known to the art, it has been impossible for the user to buy them in concentrated form and subsequently to dilute them at the time of use. This has necessitated the shipment of the materials in rather bulky form with correspondingly high freight charges.

With the foregoing in mind, the principal object of my invention may be said to reside in the provision of a material of the character described which can be prepared by 1 he manufacturer in a concentrated condition and subsequently diluted by the user. Other objects of the invention relate to the provision of a; material which is more eiiective in removing extraneous matter from the surface of the metal; to increase the coverage of such a material per unit volume; to produce a material which may subsequently be removed from the metal with greater ease; to produce a material which leaves the treated surface in a cleaner condition, better suited for receiving the subsequent coating; to reduce the cost of transporting materials of this nature, and in general to improve the art of preparing metallic surfaces for painting or similar operation.

More specifically stated, my invention has for its object the provision of a dilutible, consolute liquid admixture comprising a metal etching acid and a wetting agent that is compatible with aqueous solutions of either acid or alkali. By "consolute to a cloudy solution-a uniform solution instead of several layers or phases-a solution which does not separate on standing. v

' Before discussing the invention in greater de tail it is desired to point out that materials for preparing metal for painting are generally composed of two parts, (one) the metal etching agent (the acid), and (two) the oil solvent or disburser otherwise known as the wettingagent. The acids used must not produce deleterious results and are preferably limitedto the tri-hydric mineral acids such as phosphoric and arsenic,

but certain organic acids, such asoxalic, tartaric and citric, may also be employed. I prefer to use the tri-hydric mineral acids as they are relatively I mean a clear solution as opposedtrated, it is applied to for coating by dipping, .swabbing. Suflicient time inexpensive and produce satisfactory results without causing any objectionable after effects.

Phosphoric acid is a very commonly used etch.-

ing agent and where employed it is customary to use it as strongas it is commercially possible to obtain it. In order to produce a dilutible material in accordance with the present invention it is essential, of course, that much acid be present. I have, therefore, selected a wetting agent of great strength or effectiveness in order to reduce the quantity which it is necessary to mix with the etchingagent.

. lhe wetting agents which I prefer and which seem'to be best suited for the purpose are those sulphonicacids which have wetting agent characteristics and are compatible with solutions of either acids or alkalis. I have had excellent results by using the sulphonic acid of an aromatic hydrocarbon having an isopropyl radicalin its nucleus. The acid radical of such a body is the effective part of the molecule so I may also employ the salts of these acids. 'Neomerpin' is the commercial name of such an acid.

By way of specific example I may produce a concentrated admixture as follows:

Gallons Ortho phosphoric acid;(75% 50 Neomerpin 1.50. Water 48.50

The foregoing admixture may be used full strength or water may be added to dilute it to any desired concentration, the commercial limit being about one gallon of theadmixture to four gallons of water. i

Sulphonic acids suitable for my purpose may not be sufiiciently soluble to produce an admixture that is as concentrated as is sometimes desired, and Iptherefore, find it advisable to add to my admixture an agent for increasing the solubility of the wetting agent. Alcohols and other solvents acting in many cases like alcohols, such as ketones, ethers, esters, etc. may be employed, 7 and these. agents may be used either singly or collectively. By way of specific example of a more concentrated admixture, I may cite thefollowincz- I I Gallons Ortho'phosphoric acid- (75%). 70 Ethyl alcohol (which may be denatured) 15 Butyl alcohol- 5 10 Neomerpin 2 The foregoing admixture may be used either' full strength or diluted to any concentration up to one gallon of the admixture to about eight gallons of water.

To use my material, either dilute or concenspraying, brushing or is then allowed for it to themetal to be prepared loosen, dissolve or disperse the extraneous matter which may happen to be present, assisting its action it necessary by scrubbing with an abrasive.

The resultant residue is then removed from the.

metal by wiping with a dry cloth, by blowing 01! with steam or by washing with water. The metal is then permitted to dry in the-air or it may be dried more quickly by placing it in an oven heated to approximately 200 F. The metal is then ready for receiving the desired coating such as paint, enamel, japan or lacquer or chemically treating, to produce various phosphate or other coatings.

The above described sulphonated body is extremely effective in causing my admixture to properly wet the metal, and because its viscosity is so low only very small amounts of it, relatively speaking, are required to cover very large suri'aces. For instance it has been round that when either of the formulas above given are diluted with water to contain two gallons oi acid per gallon of diluted material, one gallon of the admixture will prepare 1.25 times as much surface as materials heretofore in use, and, in addition, the resuiting surface is cleaner and in a better condition for receiving subsequent coating.

I should like to point out that the invention is V particularly useful in preparing fabricated sheet steel automobile bodies.

I ciaimz- 1. A dilutible consolute liquid admixture for preparing metal for painting comprising tri-hydric mineral acid and a sulphonated aromatic hydrocarbon wetting agent having an iso-propyl radical in its nucleus, the same being compatible with aqueous solutions of either acids or alkalis.

2. A dilutible consolute liquid admixture or preparing metal for painting comprising phosphoric acid and a sulphonated aromatic hydrophoric acid, a sulphonated aromatic hydrocarbon wetting agent having an iso-propyl radical in its nucleus, ethyl alcohol and butyl alcohol.

- JAMES H. GRAVEIL. 

